The present invention relates to pharmaceutical compositions for the treatment of osteoporosis comprising an estrogen and a thyroid hormone as effective ingredients.
Osteoporosis is a disease which has been most notably observed among senile bone diseases and refers degenerative change by aging. In osteoporosis, a small impact leads to compression fracture of the spinal cord or bone fractures of the legs and arms, which cause pain or functional disorder.
As causes for osteoporosis, endocrine factors nutritional factors, physical factors, genetic factors, etc. have been considered; inter alia, osteoporosis sharply increases in postmenopausal women occurs at an early stage in women who underwent oophorectomy. From these facts, it is suggested that there might be a serious relationship between the incidence of osteoporosis and decrease in sex hormone, especially an estrogen, accompanied by menopause.
That is, it is known that due to the lack of an estrogen which rapidly proceeds after menopause, absorption of calcium is inhibited and at the same time, reduced synthesis of vitamin D is caused. It is thus considered that deficiency of the estrogen would be one of the important causes for osteoporosis. In recent years, an estrogen receptor was found in osteoblast so that a basis for direct action of the estrogen on bones is being clarified. In fact, the estrogen has been used in American and European countries as a first choice drug for the treatment of osteoporosis.
However, the estrogen causes unpleasant side effects such as uterine bleeding, mastoncus, etc. and might also induce endometrial cancer of breast cancer. Therefore, it is the actual situation in Japan that the estrogen has not been used very often.
During the course of investigations on safe drugs having a high therapeutic effect on osteoporosis, the present inventors have found that pharmaceutical compositions comprising an estrogen in combination with a thyroid hormone exhibit a superior therapeutic effect to the case of administering the estrogen alone. The present invention has thus been accomplished.